This invention relates to apparatus for providing indications of the removal of an object from a monitored location and particularly to such systems in which there are provided not only indications of the removal of an object from a monitored location but also indications of from which of several monitored location the object has been removed.
It is known to protect valuable objects, such as packets of currency in a bank, by providing object-sensing means placed adjacent the object to be protected so as to develop electrical signals indicative of unauthorized removal of the object, which signals may be utilized to operate alarm devices including lamps, bells, cameras trained upon the scene of the unauthorized removal, etc.
One particular application of the invention with respect to which it will be described in detail is at teller locations in banks, or at other currency-handling locations, where currency may on occasion be removed from a cash drawer without authorization, as in the course of a theft or robbery. In such applications it is known to secrete an unobtrusive object-sensing device, such as a photo-sensor of one type or another, adjacent and preferably beneath at least one of the packets of currency at each teller location. By connecting each such object-sensing device across a voltage supply, remote alarm indications may be developed which indicate the unauthorized removal of the currency, without calling attention of the unauthorized remover to the fact that his act has been detected.
One type of photo-sensor arrangement which has been proposed for this purpose is shown in the U.S. Pat. No. 3,300,770 of Brousseau, filed 10/12/64 and issued Jan. 24, 1967. U.S. Pat. No. 4,101,876 of Lurkis, filed Jan. 24, 1977 and issued 7/18/78, shows another photo-sensor type system utilizing more complex electronic circuitry, and employing a reference photo-sensing device to sense the existing ambient illumination, for electrical comparison with the illumination reaching the monitoring photo-sensor device. Neither of these patents is particularly concerned with the situation in which a plurality of objects are monitored at different locations, for example where currency in the cash drawers of a plurality of tellers in a single bank, or at the check-out registers of a store, are to be simultaneously monitored.
In the latter type of situation, we have found it advantageous to be able to provide not only the usual automatic alarm but also to provide a remote indication (preferably at a control position in the same bank or store), as to which monitored location has produced the alarm. While in some cases this may be helpful in identification or apprehension of the person performing the unauthorized removal, we have found it more usually advantageous in connection with false alarms. For example, if an authorized person such as a teller removes the monitored object unthinkingly or accidentally from its monitored location even momentarily, this will ordinarily produce a false alarm with attendant confusion, annoyance, cost and conceivably even injury in answering a false alarm. If the supervising personnel have available an indication of which monitored object, and especially if this indication is automatically caused to persist even though the monitored object is quickly replaced, then supervisory steps can be taken with respect to the person who caused the false alarm to assure that the guilty party will probably not make the same mistake again.
While persistence of the indications of the location of a removal of a monitored object even after replacement of the object is desirable for the reasons mentioned, we have found it advantageous for the alarm itself to terminate as soon as the object is replaced, to avoid irritating and disoncertingly long alarms when only a brief inadvertent object-removal has occurred.
It is also desirable in many cases to provide line-monitoring apparatus which will automatically produce an indication in the event that an open or short occurs in any of the lines interconnecting the several object-monitoring stations or connecting them to the central control box, and to provide such line-monitoring apparatus which is simple yet effective in sensing faults even when there is little difference between the potentials of the monitored lines when faulty as compared to when they are in their normal condition.
It is also generally desirable to provide a simple and reliable built-in test system which, when actuated, will provide an indication that the system is in proper operating condition, without causing the alarm to be sounded.
In practical and commercial versions of such protective systems, it is also desirable for the system to be as simple, reliable and inexpensive as possible, to use as few as possible of long runs of interconnecting cables and wires to permit as simple an installation procedure as possible, and to be at least in part modular, in the sense that identical monitoring stations may be added or removed very easily.
U.S. Pat. No. 3,638,213 of Glenn C. Dagle, issued Jan. 25, 1972 and entitled "Electrical Alarm System" discloses a bank alarm system using one or more photocells for detecting removal of a stack of bills at any of a plurality of teller locations. Each photocell is connected in series with a coil of a corresponding remote relay, and the plurality of photocell-relay coil circuits are connected in parallel with each other and provided with an alternating supply voltage from a common source. Any photocell which is rendered conductive by removal of a stack of bills from above it causes a current through its corresponding remote relay coil, which current causes the corresponding remote relay to operate, which in turn causes another remote relay to operate and produce an alarm indication of removal of the stack of bills. A remote latch circuit is also provided for each parallel circuit, which latch circuit is closed and latched by current through its associated photocell relay coil, and remains latched until a common reset switch is manually operated to break the latch circuit. Each photocell latching circuit is also connected to a corresponding remote lamp, which lamp indicates the teller station at which the stack of bills has been removed. A lamp connected across the supply voltage leads indicates when the power is turned on.
While the Dagle system is no doubt useful in certain applications, it requires a substantial number of rather long leads extending from the individual teller locations to the common control circuits for the bank. It also causes an alarm which continues until manual resetting by supervisory personnel has been accomplished, even if the stack of bills is quickly replaced, as may occur when a teller inadvertently but only momentarily lifts the stack of bills from above its monitoring photocell to produce a false alarm; such long-persisting false alarms are both irritating and upsetting, because it is impossible to distinguish them from true alarms. Furthermore, Dagle does not provide an arrangement for the sensitive detection of breaks in all of the lines interconnecting the photocells, nor any convenient arrangement for testing the entire system without causing an alarm.
Accordingly, it is an object of the present invention to provide a new and useful system and apparatus for detecting and indicating the removal of protected objects from any of a plurality of different monitored locations.
Another object is to provide such system and apparatus which provides appropriate alarm indications of when any protected object has been removed from its monitored location, and in addition provides a separate indication as to which monitored location has been subject to such object-removal.
Another object is to provide such system and apparatus in which replacement of the object into its monitored location terminates the alarm indications but does not terminate the separate indications of the location at which an object-removal has occurred.
It is also an object to provide new and useful line-monitoring apparatus which is simple yet effective, especially in combination with the remainder of the protective system of the invention.
Another object is to provide such a system including built-in test circuitry which, when actuated, will produce indications that the system is in operating condition, without giving an alarm.
A further object is to provide such system and apparatus which is relatively simple and inexpensive, easy to install, maintain, expand or contract in scope, and which requires only a relatively small amount of interconnecting wiring and parts to accomplish its purposes.